CO2咸水层封存对流混合形成机理及发展特性研究

Geological storage of CO2 in deep saline aquifer is increasingly seen as a viable strategy to reduce the release of greenhouse gases into the atmosphere. The convective mixing, in the deep saline aquifer, is a desirable process because it can significantly enhance the CO2 dissolution rates and distribution, thereby increasing storage security and capacity. Based on the CO2 storage in deep saline aquifer, we intend to develop an experiment method to measure the onset and behavior of convective mixing. The heterogeneity of porous media plays an important role to the onset of convective mixing, so two or three dimension porosity and permeability distribution will be obtained, also the relationship between porosity and permeability will be investigated. The onset mechanism of convective mixing will be investigated, including the onset time, maximum wavelength and Sherwood number. And the effect of porous media and saline solution will be analysis. During convective mixing process, the intensity and duration time for each stage are obtained. The flow properties of two phase fluids and the unstable interface will be investigated. And then the mass flux and CO2 mass transfer rate will be calculated. The influence of injection flow rate, temperature and pressure on the mass flux and CO2 mass transfer rate will also be analyzed. Finally a simple mathematic model is used to predict the mass transfer rate. The study is used to provide the data for CO2 storage in deep saline aquifer.

CO2咸水层封存是有效减排CO2、缓解温室效应的主要技术之一。CO2咸水层封存过程中，由CO2溶液和咸水的密度差引起的对流混合将增大CO2的溶解速率和空间分布范围，增加CO2的有效封存量和长期封存的安全性。本项目以CO2地下咸水层封存为研究背景，研究咸水层多孔介质渗透率及孔隙度的微观非均质性，建立描述多孔介质孔隙度和渗透率关系的经验公式；研究咸水溶液初始分布特性与多孔介质非均质性的相关性，探析温度、压力、多孔介质特性和溶液特性等对对流混合形成的影响规律，解明多孔介质内对流混合现象的形成机理；解析对流混合各个阶段的持续时间与强度的影响因素，获取不同温度与初始压力条件下CO2质量流量及传质速率，揭示对流混合发展过程中两相界面运移规律，阐明对流混合发展特性；建立多孔介质CO2与咸水溶液对流混合过程的数学模型，为实施CO2咸水层封存提供理论依据。

CO2咸水层封存是有效减排CO2、缓解温室效应的主要技术之一。CO2咸水层封存过程中,由CO2溶液和咸水的密度差引起的对流混合将增大CO2的溶解速率和空间分布范围, 增加CO2的有效封存量和长期封存的安全性。该项目研究咸水层多孔介质渗透率及孔隙度的微观非均质性，建立了描述多孔介质孔隙度和渗透率关系的经验公式。发现咸水溶液初始分布特性与多孔介质非均质性的相关性。探析了温度、压力、多孔介质特性和溶液特性等对对流混合形成的影响规律，解析了对流混合各个阶段的持续时间与强度的影响因素，揭示多孔介质内对流混合的形成和发展机理。获取不同温度与压力条件下CO2质量流量及传质速率，揭示了对流混合对CO2传质的促进作用，为实施CO2咸水层封存提供理论依据。